1. Field of the Invention
The present invention relates to a key switch serving as a safety switch used in a door lock switch or the like.
2. Description of the Related Art
A door lock switch is generally structured such as to detect an opening and closing of a door provided in an entrance door of a working area in which an automated working machine is installed and turn on and off a power source of the working machine. When closing the door, an operation key provided in the door side is inserted to a key switch provided in the entrance side, a cam body is rotated by the inserted operation key, and a switching mechanism built in the key switch is changed to a switch-on state, whereby a power source circuit or the like is connected. Further, the structure is made such that a contact point switching state of the key switch by inserting the operation key by means of a lock means is maintained, and a lock by the lock means is cancelled by pulling out the operation key if the door is opened, whereby a cam body is rotationally operated, and a switching mechanism is changed to a switch-off state, so that the power source circuit or the like is disconnected.
The key switch in the door lock switch mentioned above is generally provided with a switch main body, and a head with a key insertion port mounted on an upper end of the switch main body and attached by a screw or the like. A pair of support tables for supporting the cam are assembled in the head, a cam shaft is bridged over the support tables, and the cam body is rotatably attached to the cam shaft (refer to Japanese Unexamined Patent Publication No. 6-76675).